Publication details

Records for Logic Programming

Gert Smolka, Ralf Treinen

Journal of Logic Programming 18(3):229-258, April 1994

CFT is a new constraint system providing records as logical data structure for constraint (logic) programming. It can be seen as a
generalization of the rational tree system employed in Prolog II, where
finer-grained constraints are used, and where subtrees are identified by
keywords rather than by position.
CFT is defined by a first-order structure consisting of so-called
feature trees. Feature trees generalize the ordinary trees
corresponding to first-order terms by having their edges labeled with
field names called features. The mathematical semantics given by the
feature tree structure is complemented with a logical semantics given by
five axiom schemes, which we conjecture to comprise a complete
axiomatization of the feature tree structure.
We present a decision method for CFT, which decides entailment and
disentailment between possibly existentially quantified constraints.
Since CFT satisfies the independence property, our decision method can
also be employed for checking the satisfiability of conjunctions of
positive and negative constraints. This includes quantified negative
constraints such as y z(x
f(y,z))
The paper also presents an idealized abstract machine processing
negative and positive constraints incrementally. We argue that an
optimized version of the machine can decide satisfiability and
entailment in quasi-linear time.